Apparatus for coating paper board



June 21, 1955 l VA. L. BAUUNG 2,711,156

APPARATUS RoR coATING VPAPER BOARD.

y RiledMay 17, 1952 INVENToR.

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United States Patent@1i` 2,711,156 Patented June 2 1, 1955 ice APPARATUS FOR COATING PAPER BOARD Adrianus L. Bauling, Deventer, Netherlands, assignor to American Viscose Corporation, Philadelphia, Pa., a corporation of Delaware Application May 17, 1952, Serial No. 288,470

Claims. (Cl. 118-60) The present invention relates to apparatus and methods for making coated paperv Yand paper boards that are adapted to be printed and/or lacquered and to be made' A into cartons and boxes either before or after such printing and/or lacquering for the purpose of packing such things as foodstuffs, cosmetics, drugs, hardware and other articles for sale. 1

Whereas both strawpaperboard and chipboard have heretofore been used for these purposes, the strawpaperboard has generally had restricted application because of the difliculty of imparting to it a sufficiently water repellent and less absorbent surface which is capable of accepting printed matter. Chipboard, on the other hand, has found wide acceptance for these purposes since it is capable of receiving printed matter without blurring. Chipboard, however, is an expensive product since it essentially consists of a laminated board having one ply of high quality sulte paper with another ply of a high grade kraft paper sheet coated with casein and china clay.

It is an object of the present invention to provide an apparatus and process for producing a high quality ofv paper and of paperboard from relatively inexpensive, low quality paper or paperboard stock, such as strawpaperboard, which are so highly absorbent that they would disintegrate if immersed in water and moved therein without being completely supported along one or both surfaces thereof. Another object is to provide 'l' a paper of the type just mentioned which is capable of receiving printed matter without blurring of the outlines thereof. Another object is to provide an apparatus and l.

method for making a relatively inexpensive high quality paper or cardboard suitable'for the boxes and the like.

Generally, the system of the present invention involves means for passing a continuous length of paper board, such as strawpaperboard, through a series of means for production of cartons, f

treating the sheet on one side only, and subsequently-5"? through means for drying the treated sheet with means disposed at the entrance to such drying means for directing the sheet to the drying means in such a .manner that its treated face is applied to a smooth heated surface travelling therewith. After thus drying the sheet,`-3l

means is provided for rehumidifying the sheet and there is means for taking up the sheet such as by winding. The series of treating means comprises means for applying a highly viscous coating composition to one surface only of the sheet and means disposed subsequently thereto along the path of travel of the sheet for spraying liquids against the coated surface only of the sheet. The arrangement is such that the viscous coating first applied to the face of the sheet protects the sheet from the sprays subsequently applied for the purpose of coagulating, neutralizing, washing, or otherwise treating the coating carried on the sheet.

The single figure of the drawing is a diagrammatic side elevation of the apparatus of the present invention.

As shown in the drawing, a roll of paper, such as titl Aaqueous 10% sulfuric acid at 2,5 to 45 thereby convertit into a lthin strawpaperboard, is rotatably mounted in bearings 3 at one end of `the machine. This roll of paper 4 serves as the supply for the machine and the sheet 5 which is continuously unwound and drawn oif from the supply roll proceeds first about a guide roll 6 and then downwardly under a guide roll 7 and then up over a guide roll 8. Means is provided for applying a viscous coating material to the exposed surface of the sheetV as it proceeds under the guide roll 7.A This means may comprise a tank or container 9 in the form of a trough extending transversely of the machine which contains a solution of the viscous coating material hereinafter defined. A roll 10 is rotatably mounted so that vit ispartially submerged or immersed inthe viscous solution in container 9. It is urged upwardly against the surface of the paper carried around roll 7 by any conventional means, such as by springs 10a acting upwardly upon trunnions extending -from the roll. Other vmeans can be employed for applying the solution to one side of the sheet, such as a'spray device, the reverse-roller system etc. The viscous solution applied by theV roll 10 may be any alkaline solution of a water-insoluble, alkali-soluble cellulose ether, such as methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, or mixed ethers such-as ethyl hydroxyethyl cellulose ether. The solution may contain from 2 to 10%,or more of the cellulose ether and from 2l to 10% of sodium hydroxide and it may also contain pigments to impart any desired color to the coated surface. The pigments that may be employed include china clay, barium sulfate, calcium sulfate, zinc oxide, titanium dioxide or others.y The composition may also contain dyes, fillers, and it may contain collodial binder material of other types in addition to the cellulose ether, such as casein, gelatin, polyvinyl alcohol, or the like. However, it must contain the cellulose ether. A preferred composition for application by the roll '10 consists `of 19% china clay, 11% barium sulfate, 5.5% sodium hydroxide, 4.3% hydroxyethyl cellulose, vand 60.2% water, the cellulose ether being insoluble in water but dissolved in the alkaline solution to form a viscous composition.

Surplus coating may be removed as the paper proceeds from roll 7 to roll 8 by means of a doctorf'blade 11 against which the paper may be held by means of @a backing bar 12. Instead of wiping off vthe surplusat 11 or in addition thereto, excess'may be removed by a doctor blade 13 discharging into areceptacle 14, the paper. preferably beingbacked up and supported at this point by suitable means such as a belt 15 operating about driven rolls 16 and 17..v -Spray means 181s disposed adjacent the lower portion of therdownward course of travel of the paper as it proceeds from thetrollv 8 about the lower roll 19. A receptacle 20 may be disposed under roll 19-so that kit extends under the spray 18 and catches drippings from this stage of the apparatus. The spray 18 may apply a dilute acid such as C., but pref- C. to coagulate the cellulose ether and gel film adhering to the face of the sheet. The spray 1S, vlike the coating roll 10, extends transversely of the machine at least the full width of the sheet carried therethrough. 'From the roll 19, the sheet carrying the gel lm on itstlower surface proceeds about the guide rolls 211, 22, 23, 24, 25 and erably about 35 26 to the drier which comprises one or more rotatablyV internally heated as i't proceeds under roll 22. The spray means 31 may be water to wash tout the acid previously applied by spray 18.

Additional spray means may be provided as at 33 and 34 for applying a 5% sodium bicarbonate solution and then water or, if desired, water in both cases. The use of a bicarbonate solution Vis preferred to assure neutralization of any residual acid left in the sheet after being Washed by the spray means 31. Spray means 33 and 34 may be provided with separate catch basins, but as shown, a common receptacle 35 is shown for receiving drippings from both sprays and from the biglit of the paper extending under roll 24.

The spray means 18, 31, 33, and 34 serve to coagulate and neutralize the viscous cellulose ether solution applied by the roll 1t] without ever really soaking the back portion of the paper sheet thus coated and treated. This is absolutely essential in order to avoid rupturing of the sheet as it proceeds between successive rolls of the machine.

Means comprising the guide roll 26 is allowed to direct the sheet to the drying drums so that the coated surface of the sheet will be placed in direct contact with the heated surface of the drums at the initial stage of drying. This assures the production of a smooth face on the coated side of the sheet by'causing the vapor developed to pass through the porous uncoated back face of the sheet. The initial drying on the rst drum removes the largest portion of the moisture so that the smooth surface that develops on the coated face of the sheet is retained through the subsequent stages of the drying operation.

After drying to a moisture contentof about 2 to 6% the sheet proceeds from the drier over guide rolls 36, 37 and 38 to a take-up device, such as a driven Winding core 39 supported in bearings 40 at the end of the machine. If desired, humidifying means may be provided at 41 adjacent the course of the sheet between rolls 37 and 38 to restore the moisture content of the sheet to a value of about 4 to 6% in case excessive drying occurs. Such humidification avoids the development of brittleness and the tendency to crack as the material is wound on the core 39.

The product thus produced is a high quality paper or paperboard far less expensive than the coated paper or chipboard of the prior art and is practically equivalent in quality and appearance, particularly in respect to its ability t accept printing without blurring. The system of the present invention when employing the preferred composition mentioned hereinabove results in an increase in weight of l2 grams per square meter when the initial paper weighs 237 grams per square meter and the composition of the increment is 56% china clay, 32%

barium sulfate, and 12% cellulose ether. The system of the present invention renders the paper white and smooth. The final product is less absorbent, greaseproof and strengthened as compared to the untreated stock. It is adapted to be printed by odset or intaglio without blurring and running of the inks and it can be lacquered with a single lacquer or varnish coating without encountering the difficulty of having the lacquer or varnish sinking into the paper stock.

The product is useful for making small cartons for` foods, pharmaceuticals and which enclose tubes ofV toothpaste and cough drops, breakfast foods, etc. When the coating is applied to strawpaperboard, the cartons are useful for packing all types of commodities-soap powders, breakfast foods, hardware, bakery products, etc., all of which products' now employ a strawpape'rboard laminated on the outside to a sheet of kraft paper which is then coated with a p The present processrnakes an equivalent product without the necessity of Vusin'gthe sheet of kraft paper and thus achieves a substantialv china clay glue composition.

economy.

It is to be understood that changes and variations may be made without departing from the Yspirit and scope of the invention as defined in the appended claims.

I claim:

1. Apparatus for treating paper and the like comprising means for supporting a supply roll of paper, guide. rolls for leading the paper in a zigzag paththrough Vthe machine, means beneath a portion of the path forY applying a viscous composition comprising 'anaqueous alkaline solution of a water-insoluble, alkali-soluble cellulose ether to the lower one face onlyof the paper as it proceeds through said path, spray means disposed exclusively-beneath said path subsequent to said applying means, dry-v ing means comprising at least one driven internally heated cylindrical drum beyond said spray means, guide means adjacent the point of Ventrance to the drier means for directing the sheet to the rst drier drum with kits treated surface in contact therewith, and means beyond the drier means for winding the paper on a core.

2. Apparatus according to claim l'comprisingwi'per means extending transversely of the sheet ata point of its path beyond the applying means, and means on the side of the sheet opposite thatengaged by the wiper* means for backing up or supporting the sheet at the position of wiping.

3. Apparatusas defined in claim 1 in which receptacles are disposed beneath each of said spray means.

4. Apparatus as defined in claim 1 comprising Vguide rolls arranged in an upper region of the machine between" the supply supporting means and the drying means and intervening guide rolls are disposed each below the region occupied by the nearest two upperV guiding rolls, thereby Y forming downwardly extending loops in the sheet, and,

the applying means and spray means are disposed alongside a respective one of said loops beneath the sheet as itV travels therethrough.

5. Apparatus as delined in claim l comprising guide rolls between the drying means and the take-up meansV and humidifying means mounted adjacent the course `of the sheet with respect to the last-mentioned guide rolls.

References Cited in the le yof this patent UNITED STATES PATENTS drugs such as the small boxes` Calton Jan. l, '19,52 

1. APPARATUS FOR TREATING PAPER AND THE LIKE COMPRISING MEANS FOR SUPPORTING A SUPPLY ROLL OF PAPER, GUIDE ROLLS FOR LEADING THE PAPER IN A ZIGZAG PATH THROUGH THE MACHINE, MEANS BENEATH A PORTION OF THE PATH FOR APPLYING A VISCOUS COMPOSITION, COMPRISING AN AQUEOUS ALKALINE SOLUTION OF A WATER-INSOLUBLE, ALKALI-SOLUBLE CELLULOSE ETHER TO THE LOWER ONE FACE ONLY OF THE PAPER AS IT PROCEEDS THROUGH SAID PATH, SPARY MEANS DISPOSED EXCLUSIVELY DRYNEATH SAID PATH SUBSEQUENT TO SAID APPLYING MEANS, DRYING MEANS COMPRISING AT LEAST ONE DRIVEN INTERNALLY HEATED CYLINDRICAL DRUM BEYOND SAID SPRAY MEANS, GUIDE MEANS ADJACENT THE POINT OF ENTRANCE TO THE DRIER MEANS FOR DIRECTING THE SHEET TO THE FIRST DRIER DRUM WITH ITS TREATED SURFACE IN CONTACT THEREWITH, AND MEANS BEYOND THE DRIER MEANS FOR WINDING THE PAPER ON A CORE. 